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1,2

Column 3 of A212855.

R. H. Hardin, Table of n, a(n) for n = 1..210

Empirical: a(n) = 10*a(n-1) -27*a(n-2) +18*a(n-3).

Explicit formula: a(n) = 6^n-2*3^n+1. - Vaclav Kotesovec, May 31 2012

Some solutions for n=3

..1..2..0....2..1..0....0..2..1....1..2..0....1..2..0....2..1..0....1..2..0

..2..0..1....2..0..1....2..0..1....2..0..1....0..2..1....2..0..1....1..0..2

..0..2..1....0..1..2....2..1..0....2..1..0....2..0..1....0..2..1....0..2..1

Sequence in context: A217215 A159682 A197500 * A215115 A142128 A158966

Adjacent sequences: A212847 A212848 A212849 * A212851 A212852 A212853

nonn

R. H. Hardin May 28 2012

approved